How can you measure heat output on a Austroflamm Integra?

[LuvMyStove]

Thanks again to all of you who helped me identify that my air sensor was damaged. If you haven't seen my latest post, the stove is hotter than blazes now.

I'm sure someone has asked my new question, but I can't find it on the site:

I want to measure the approximate heat output of my Austroflamm Integra. The stove's book says 30,000 btus, if I remember right, but I want to test several brands of pellets and try to find which produces the most heat in our stove. If one brand gives us 31,000 btus and another brand only gives us 29,000, it would be good to know?

Is there any type of gauge I can locate that could be set in front of the stove's hot air output that would give me an indication of that? I thought of trying a thermometer, but I doubt it would be sensitive enough to detect the difference in output. Thanks again.

 

[LuvMyStove]

To add to my post, here's is why I really want to know which brand works best in our Integra. We just got this price list from our dealer here in Conn.:

Prices per ton
$219 Maine's Choice premium grade
$219 Energy Hardwood premium grade
$249 Hamer's Hot Ones super premium grade
$259 Geneva Ultralow ash super premium grade
$259 Okanagan super premium grade
$259 Turman 100% oak super premium grade
$269 Barefoot super premium grade

This year we used Hamers and Barefoot. Both burned well. In fact, the only brand our stove didn't seem to like was North Country (I think that was the name). With those, we could tell a marked difference in heat output and way, way too much ash. Instead of cleaning the stove and pipe every other month, it was every 3 weeks.